Sick and still training? A risky game with your health
Myocarditis, drop in performance, relapse - why training with an infection is dangerous
Feeling "not quite fit" but still don't want to lose your rhythm? Be careful: even light exercise during an infection can weaken the immune system - and in the worst case, attack the heart. In this article, you can read about what really happens in the body, how to recognise warning signs and why taking a break is sometimes the best form of progress.
The body under stress: what infections do to the organism
Infections - whether flu-like, gastrointestinal or COVID - are nothing more than alarm states in the body. The immune system runs at full speed to fight intruders such as viruses or bacteria. Pro-inflammatory messenger substances are released, fever can occur and energy is mobilised - not for performance, but for defence. If you train during this phase, you expose your body to additional stress, which can be dangerous.
Particularly treacherous: you may only feel a little run down or have a cold - but internally the body is in full crisis mode. And this is not compatible with training that gets your heart rate up or demands muscle work.
Heart in danger: myocarditis as a silent threat
Myocarditis, an inflammation of the heart muscle, is one of the most feared complications after viral infections. Viruses such as Coxsackie viruses or influenza pathogens can attack the heart directly - especially if you don't take it easy. Spread myocarditis often remains undetected, but can lead to cardiac arrhythmia, reduced performance or even sudden cardiac death in the long term.
Typical symptoms of myocarditis:
- - Persistent fatigue and weakness
- - Heart stumbling or palpitations
- - A feeling of pressure in the chest
- - Shortness of breath with little exertion
A sports medical screening is essential in case of suspicion.
Not just a cold: stomach bug & co. also require a full break
Gastrointestinal infections such as stomach flu are particularly insidious. Diarrhoea, vomiting and loss of fluids quickly lead to an electrolyte imbalance, which can impair the function of the heart, kidneys and muscles. If you return to sport too soon, you risk circulatory problems, muscle cramps or even collapse.
The same applies here: only when the digestive tract is fully functional again and the body and energy levels have stabilised should training be considered. The return should be gradual - ideally under observation of your own body.
How to correctly categorise warning signs
There are some simple but important rules for assessing whether your body is ready for exercise.
No-go symptoms for exercise:
- -Fever
- -aching limbs
- -Sore throat with difficulty swallowing
- -Exhaustion
- -Sore throat with difficulty swallowing
- -Diarrhoea and/or nausea, vomiting
Caution also with:
- -Irritating cough or shortness of breath
- -Resting pulse rate significantly above normal
- -Unusually high resting blood pressure
However, if you only have a mild cold without any general symptoms, a short walk or light stretching may be acceptable - but no training with an increased heart rate.
What happens in the body during and after infections
During an infection, the immune system runs at full speed. There is an increase in inflammatory markers, a change in cytokine release and often a temporary drop in physical performance. The body prioritises defence - not muscle building, fat burning or VO2max improvement.
After the infection, the body is initially weakened as energy reserves are reduced and repair processes are ongoing. During this time, it is crucial to get enough sleep, eat high-quality food (especially protein, vitamin C, zinc and omega-3 fatty acids) and reduce stress.
Sport acts like a booster. What passes for a harmless infection in everyday life can turn into a systemic crisis through physical exertion. The reason: exercise increases pulse, blood pressure and respiratory rate. The pathogens are thus distributed more quickly throughout the body, while the exercise-induced increase in cortisol simultaneously reduces the immune response. The perfect scenario for a so-called "carry-over".
In addition, the muscles are often not fully functional during infections - this not only affects the arms and legs, but also the heart muscle. Exercising despite an infection can cause long-term damage to your heart.
The right way to return to work after an infection
Even after the symptoms have subsided, the body is still in regeneration mode. The rule of thumb in sports medicine: 48 hours completely symptom-free before you start exercising again - and moderately at that:
- -Walks in the fresh air
- -Light mobilisation exercises
- -Short yoga or breathing sessions
Only when this is well tolerated can endurance training be slowly resumed. High-intensity strength training should be avoided for up to a week after full recovery.
Tips for practice
- Don't see a break from training as a step backwards. It is a sign of body intelligence and protects you from long-term damage.
- Become your own body scanner: look out for subtle signals such as an increased morning pulse rate or unusual tiredness.
- Take regeneration seriously: Consciously treat yourself to periods of rest - with walks, breathing exercises or meditation.
- If in doubt, seek medical advice. Especially in the case of infections with chest pain or heart symptoms.
- Keep your training plan flexible: Adapt your workload to your state of health - not the other way round.
Psychological component: The fear of losing something
Many ambitious athletes are afraid of losing muscle mass or endurance by taking a break. But this worry is usually unfounded. Studies show this: After a 7-14 day break, the loss is minimal - and is usually made up after just a few sessions. It is more important not to risk any consequential damage that causes months of downtime.
Tip: Make conscious use of this phase for regeneration, sleep, conscious nutrition and mental relief. Those who return with a clear head and a strengthened body will train more effectively and sustainably.
The break is part of the plan
Training is only healthy if it is in harmony with the body's signals. If you train with an infection, you risk inflammation, heart damage and long periods of absence. A consistent break, a smart return and trust in your own body are signs of maturity - not weakness.
So the most important rule is: heal first. Then train.